Electric furnace or oven.



No. 736,509. l 'PATENL'ED A'Ubr. 1U, wuo. A. EIMER.

ELECTRIC FURNAGE 0R OVEN.

APPLICATION FILED MAX 22. 1903.

I0 IODEL. 2 SHEETS-SHEET 1.

No. 736,509. PATENTED AUG. 18, 19u15.

- A.'BIMBR.

ELECTRIC PURNACE 0R OVEN.

APPLIUATION FILED un 22, 1903. Io 101m., 2 SHEETS-sum 2.

NITED STATES Patented August 18, 1903.

AUGUST EIMER, OF NEW YORK, N. Y.

ELECTRIC FURNACE R OVEN.-

SPECIFICATION forming part of Letters Patent No. 736,509, dated August18, 1903.

Application filed May 22,1903. Serial No. 158,225.v (No model.)

- invented certain new and useful Improvements in Electrical Furnaces orOvens, of which the following is a specification.

rlhis invention relates to electrical furnaces or ovens wherein smallarticles-such as artificial teeth, bridgework, gums, chemists crucibles,and the like-may be baked or heated; and the main features of my saidin-A vention may be briefly summarized as follows: First, theconstruction of an article of the character indicatedV of relatively fewparts in the interests of simplicity and economy; second, the provisionof an integral oven closure and support for the articles to be heated,whereby both of said elements may be removed at one time; third, theprovision of a removable oven-plate of refractory material havin gdepressions containing an exposed electrical resistance-conductor andhaving increased heating efciency.

The invention further includes the novel features of construction andarrangements of parts, as will be fully described hereinafter andparticularly pointed out in the claims.

In the drawings accompanying this application, Figure l is a perspectiveelevation of my improved velectrical furnace or oven. Fig. 2 is alongitudinal sectional view thereof. Fig. 3 is a detail plan view,partly in horizontal section, of the heating-plate. Fig. 4 is alongitudinal section broken away, showing the dome or cover minus theback closure. Fig. 5 is an end view of a base-plate and a modified formof heating-plate, wherein the under side of the latter member isrecessed and provided with a non-conducting packing. Fig. 6 is across-section taken on the line 6 6 of Fig. 3; and Figs. 7, S, and 9 arelike views showing modified forms of conductor arrangement. Y

As premised, one of the main features of myinventon lies in theemployment of as few parts as possible in producing the improved furnaceor oven. To this end I provide a base-plate, as a, said plate being ofsuitable refractory material and having the recessed side edges h h toreceive the lower ends of a dome-like or other shaped housing or cover oof similar material, which latter, either with or without the back plated, is produced as one integral member, or said cover and base may beproduced integrally. The heating member is in the form of a plate, as e,of suitable refractory material of dimensions enabling it to slidewithin the oven upon the base-plate a. Said lneniber e is provided uponits upper surface with a series of grooves or channels, asf, forming, infact, a corrugated or serrated surface of enlarged heating area for saidmember. rWithin said grooves or channels f is laid a resistanceconductor`q--as, for example, a platinum wire-to assume incaudescence with theflow of a suitable electrical current.

As a means of arranging and securing the conductor g within the severalgrooves f I preferably cause the opposite ends of said grooves toterminate, respectively, at points anterior to the perimeter of membere, and I cause the substance of said member intermediate said groovesand its perimeter to be pierced horizontally, thereby permitting thethreading of conductor g to and fro through the opposite endperforations in the manner indicated in Fig. 3, forming, as it were, agrid of heating-strands. The opposite terminals of conductor g maybeprovided with binding-posts (not shown) or may be otherwise suitablyconnected in an electrical circuit.

As will be clearly perceived by referring to Fig. 6, each strand ofconductor g is partly inclosed by a groove f, the walls of adjacentgrooves separating different sections of said conductor and saidgrooves, according to their depth, increasing the surface area of membere, thus enlarging its capacity to receive and yield heat energy obtainedfrom the incandescence of conductor g and permitting direct heatradiation from said conductor to the oven interior. I may furtherenhance the heat production by providing in another plane of the membere an additional conductor, which may be connected in series withconductor g, or if either of said conductors are required to be usedindependently they may be in multiple connection with the source ofcurrent.

In Fig. 7 I have shown a plate e, having its surface provided with thegrooves f, contain- IOO latter is threaded to and fro through somev orall of said perforations and has opposite terminals capable of makingelectrical connections either in multiple or in series with theconduetorg. With the additional or auxiliary conductor il embeddedwithin the plate e it is evident that the degree of heat obtainable fromsaid plate can be intensified.

The interior surface of the dome or cover c may be recessed orcorrugated in a similar manner to member e and provided with acorresponding resistance-conductor,orsaid dome may be piercedlongitudinally, as seen in the drawings, whereby the conductor, as j, asthreaded within the perforations indicated is thus embedded in thematerial of which the dome is composed. The opposite terminals ofconductor j may connect with binding-posts (not shown) convenientlylocated or maybe otherwise suitably included in an electrical circuit.The rear closure-plate d may, as seen in Fig. 2, be produced integrallywith the dome, or said plate may be a separable member, or, as seen inFig. 4, said rear plate may be eliminated altogether or when used may,if desired, be provided with a resistance-conductor.

The forward closure of the furnace or oven consists of a plate Z, ofrefractory material and of like contour to the arch of the dome orotherwise, to fit about and close the ovenopening. Extending from saidclosure l isa shelf orsupport m for the articles to be heated, whichsupport is either formed integrally with said closure (see Fig. 4) or isconnected thereto, by fitting, at its narrowed portion within a recessin the base of said closure. (See Fig. 2.) When the support m is formedseparately and fitted to the closure, indicated in Fig. 2, it has arearward extension, as n, which is provided with an engaging means, asan aperture 0, Within which latter the bent or hooked end of a tool maybe inserted for the purpose of removing the closure Z and withdrawingthe support m. Alscwhen the closure Z and support m are produced as oneintegral member then the rearward eX- tension n, as shown in Fig. 4, maylikewise be produced integrally therewith. The support m is located andarranged with relation te the closure Zand when inserted within the ovenis in such relation to the heating member e as to lie superposed uponand over the latter.

The closure Z or the forward end of the dome may be provided withgrooves, as r, for the passage or reception of the conductor-terminals,although, as is evident, such arrangement is by no means arbitrary andmay be modified to suit requirements, or bindingposts for saidterminals`may be suit-ably provided.

I provide a peep-hole, as p, in the closure Z, and instead of fittingsame with a removable plug, as is the present method, I preferably fttherein a disk of fused quartz or other transparent substance permittinga visual. indication of the interior heated condition of the ovenwithout removing the closure.

As seen in Fig. 5, the plate e is recessed at its under side, leaving aclearance intermediate said plate and the base-plate a to retard theabsorption of heat by the latter member, and also'in lthe furtherance ofsaid end I may insert a packing of non-conducting material, as asbestos,within said recess.

In the operation of my invention I fit the aforesaid parts together,placing the dome upon the base-plate, laying the articles to be heatedupon the support m, and moving the closure Z to cover the entranceto-the oven with the support 'm entered therein. The current is thenswitched on either to the conductor or conductors in plate e alone oralso to the conductor in the dome, and during the operation of thefurnace the color of the firing can be discerned through the peep-holep. If desired to test the articles being heated, it is only necessary todraw away the closure by the extension fn, by which act the support m isbrought outside the oven in full view. The dome-like interior contour ofthe cover serves to concentrate the heat received thereby directly uponthe articles held by support m.

As seen in Figs. S and 9, Ihave illustrated two other means of applyingresistance-conductorsto the plate e and which means are equallyapplicable in fitting resistance-conductors to the other refractorymembers of the furnace. For instance, in Fig. S I show the grooves g,within which conductor f is sunk, as provided with the overhanging edgess to better retain said conductor within said grooves when expanded byheat. Also in Fig. 9 I show a heating-plate as formed of two opposedmembers t and et, provided with corresponding grooves upon their meetingsides, whereby when said members are fitted together they may receive orinclose or embed between them a resistance-conductor,as g.

Having now described my invention, I declare that what I claim, anddesire to secure by Letters Patent, is-

1. An electrical furnace or oven composed of a permanent base-plateforming a bottom, an integral housing fitting removably thereabout, aforward removable closure therefor, and a removable conductor heatingmember.

2. An electrical furnace or oven composed of a permanent base-plateforming a bottom, a dome-like housing, fitting removably thereover, aforward removable closure, and a removable conductor heating member.

3. An electrical furnace or oven composed of a permanent base-plateforming a bottom, a dome-like, rearwardly-closed housing, fittingremovably thereover, a forward removable closure, and a removableconductor heating member.

4t. The combination with an electrical fur- IOC IOS

IIO

nace o`r oven of a combined closure and shelf therefor comprising acover member having an inwardly-extending support for the articles to beheated.

5. The combination with an electrical furnace or oven of a combinedclosure and shelf therefor comprising. a cover member having aninwardly-extending support for the articles to be heated, and a rearwardextension. v

6. The combination with an electrical furnace oroven, ofa combinedclosure and shelf therefor comprising a cover member having an integral,inwardly-extending support for the articles to be heated.

7. The combination with an electrical furnace or oven, of a combinedclosure and shelf therefor comprising a cover member having an integral,inwardly-extending support for the articles to be heated, and having anintegral rearward extension.

8. In an electrical furnace or oven, a removable heating member composedof a plate of refractory material having a resistanceconductor disposedin an open recess in its surface, and non-closing means preventingdislodgment of said conductor when expanded.

9. In an electrical furnace or oven, a removable heating member composedof a plate of refractory material bearing a series ofparalleldepressions, to enlarge its surface area, a resistance-conductorlocated in said depressions, and non-closing means preventingdislodgment of said conductor when expanded by heat.

10. In an electrical furnace or oven, a removable heating membercomposed of a plate of refractory material, a series of parallel,partially-overhung, open grooves sunk in the surface thereof, the endsof said plate, between its perimeter and the respective opposite ends ofsaid grooves'being provided with horizontal perforations, and aresistance-conductor threaded through said perfcrations, and lyingwithin said grooves, said conductor being thus capable of radiating heatout- Wardly from said grooves.

1l. In an electrical furnace or oven, a removable heating membercomposed of a plate of refractory material having an open recess in itsheating-surface, and a resistance-conductor disposed in said recess, thematerial bounding the recess at opposite sides extending partially overthe opening thereof; together with an auxiliary resistance-conductorembedded in said member.

12. In an electrical furnace or oven, composed of a base-plate forming abottom, and an integral housing fitting removably thereabout, a heatingmember having a series of depressions in its heating-surface, and aresistanceconductor located in said depressions; the reverse surface ofsaid member be ing recessed, and containing a packing of non-conductingmaterial.

13. In an electrical furnace or oven, composed of a base-plate forming abottom, and an integral housing tting removably thereabout,abase-plate,a removable heating member composed of a plate of refractorymaterial, having a series of parallel grooves in its heating-surface, aresistance-conductor disposed in said grooves, and a layer ofnon-conducting material interposed between said.

base-plate and the reverse surface of said heating member.

14. In an electrical furnace or oven, a wall thereof having anobservation-opening, and a transparent covering of fused quartz for saidopening.

15. In an electrical furnace or oven, composed of a base-plate forming abottom, and an integral housing fitting removably thereabout, a heatingmember composed of a pair of superposed plates of refractory materialbearing alined depressions in their respective, opposed surfaces, and aresistance-conductor inclosed between said depressions.

Signed at New York this 11th day of May,

AUGUST EIMER. Witnesses:

F. W. BAKKER, JACOB B. TOCH.

